Appliance for rolling screw threads



Patented June 11, 1940 UNITED STATES PATENT OFFICE George Gould, Birmin gham, England, assignor to Wolseley Motors Limited, Birmingham,

England Application July 20, 1939, Serial No. 285,546 In Great Britain May 25, 1939 6 Claim.

This invention relates to tools or appliances for rolling screw threads on revolving work-pieces, of the kind comprising a plurality of threaded rolls rotatably mounted upon a holder or support and adapted to be engaged with the work so as to roll a screw thread in the surface thereof.

The object of the present invention is to provide locating means whereby the thread-forming rolls of the device or appliance are automatically brought to rest, after each operation, in such angular relationship that they track" correctly; that is to say, so that they generate one and the same track or thread on contacting with the work-piece.

Figure 1 of the accompanying drawing is a transverse vertical section through a thread-rolling tool in accordance with the present invention. a

Figure 2 is a plan view.

Figure 3 is a horizontal section on line III-III, Figure 1.

Figure 4 is a vertical section on line IV--IV, Figure 2.

Figure 5 shows the spring-loaded locating lever in side elevation, plan and end view.

Referring to the drawing, the improved or modified thread-rolling tool comprises two verticallyspaced threaded rolls I, I, formed integral with or pressed tightly on to pins or spindles 2 which are freely mounted to revolve in bearings 3 in the spaced side cheeks 4 of a carrier head or block 5. One end of each pin or spindle 2 projects from the side of the carrier block 5, this projecting end of the pin being fashioned to form a transverse V-shaped or wedge-like extremity 6, of double-bevel form.

Pivoted on vertical pins 1 carried by pairs of lateral lugs 8 (Figure 4) on the side of the carrier block, are two levers 9, adapted to co-operate with the respective roll pins 2. Each lever 9 is provided at its forward end with a V-shaped projection I which itself is formed with a longitudinal V-sectioned groove I I which is normally engaged by or mated with the V-shaped end 6 of the corresponding roll pin 2 when the rolls are not in operation. The rear end of each lever 9 is extended to form an abutment for a spring I2 housed in a recess in the carrier block 5, said spring maintaining the V-shaped part III of the lever in engagement with the end of pin 2.

The carrier block 2 is pivotally mounted upon a holder or support I3 adapted to be bolted to a traversing or feed slide on the machine, and for this purpose a key-hole sectioned bar I4 is fitted within a correspondingly shaped transverse slot formed in the back of the carrier block and turns upon a pin I supported by the side cheeks I6 of the holder I3. The lower part of the carrier block 5 may engage an adjustable stop pin IT. The work-piece (not shown) is conveniently 5' bar stock fed intermittently through the spindle oi the machine, and when the stock has beenfed forward the holder I3 is arranged to be fed laterally towards it to cause the stock toenter between the rolls I, I, into contact therewith 10 whereby a continuous thread is rolled upon the. surface of the work.

When the tool is not operating, the V-shaped end Ii of each roll pin 2 is in full engagement with the V-groove II of the projection III of the corresponding lever 9, the pressure of the'spring I2 tending to-retain it in such full engagement. When the rolls I, I, are brought into contact with the revolving work-piece the said rolls and their pins or spindles 2 are revolved, and the transverse 80 V-shaped end 6 of each pin 2, by acting on the edges of the cam-like sloping surfaces formed by the V-groove II in projection I0, causes the lever 9 to rock on its pivot 1 against the action of the spring I2. On completion of the threadrolling operation the tool is withdrawn'from the work and the co-operation of the inclined or camlike edges of projection III on lever 9, with the wedge-like or bevelled end 6 of pin 2, causes the said pin 2 to turn into such an angular position that its bevelled or V-shaped end 6 is in full engagement with the groove II or the lever, as in Figures 2 to 4, being retained in such full engagement by the pressure exerted by the spring I2. The angular relationship of the flats on the V-shaped end 6 of the pin to the thread of the roll I is so determined that when both levers 9 are in full engagement with their respective pins the threads on the two rolls forms a single track on the work-piece.

Owing to the end thrust on the pins 2 set up by the springs I2lit is found that the consequent friction between the ends of the rolls I and the carrier block may sometimes be sufllcient to prevent the free return of the rolls after operating 45,

on the work, and in order to ensure such free return means may be included for reducing this end thrust. Thus, in the example shown, a counter-acting spring I8, fixed to the carrier block, acts upon the end I9 of each pin 2 in an axial 5o direction opposite to that in which the spring I2 acts, thereby relieving or reducing the pressure between the roll and carrier faces and ensuring a quick return of the rollers to their correct initial positions. 86

Small adjustments of the distance between the rolls l, I, may be effected by set-screws 20 bearing upon the bar H and which, by their reaction, slightly deflect the comparatively thin portion 2i (Figure 1) of the carrier, causing the rolls to approach or recede from one another ac cording to the adjustment of the set screws.

As to the functioning of the opposed cam surfaces when the projection of one member is at to the axis of the notch in the other member, there is no tendency for the members to remain in this position so long as neither apex is fiattened. When correctly formed any effort to get the two apices to remain in contact with each other by deliberate setting, fails. Further, any wear of the engaging surfaces tends to sharpen the apices rather than to form flats on them.

In a modification, the lever 9 may carry a V-shaped transverse projection engaging a V- sectioned groove in the end of the roll pin, this being the reverse of the arrangement hereinbefore described. Also, instead of employing the levers 9, spring-loaded plungers, prevented from rotating, may be used, said plungers being shaped to co-operate with the roll pins so as to return the latter to given initial positions in the manner herein described.

What I claim is:

1. An appliance for rolling a screw thread upon a revolving work-piece comprising a roll carrier movable laterally towards the work, a pair of spaced and free or independent screw-threaded rolls rotatably mounted upon the carrier, and spring-influenced devices exerting pressure upon parts turning with the rolls, a cam surface being provided upon one of the engaging parts co-operating with the other part to cause the rolls to come to rest in predetermined relative angular positions.

2. An appliance for rolling a screw thread upon a revolving work-piece comprising a roll carrier movable laterally towards the work, a pair of rotating spindles, mounted upon the carrier, screwthreaded rolls rigid with the spindles, and a spring-loaded member engaging an end of each spindle, the ends of the spindles and the engaging parts of the spring-loaded members being so shaped that, as the rolls rotate, the said members are displaced in the axial direction of the rolls and, after operation of the .rolls upon the work, cause, by their co-operation, the rolls to come to rest in predetermined relative angular positions.

3. An appliance for rolling a screw thread upon a revolving work-piece comprislnga roll carrier movable laterally towards the work, a pair of rotating spindles mounted upon theacarrier, screwthreaded rolls rigid with the :sp'in'dles, two levers pivoted upon the carrier, and springs acting on the levers to press them respectively into engagement with ends of the roll spindles, the said ends of the spindles and the engaging parts of the levers being so shaped that, as the rolls rotate, the said levers are moved angularly and, after operation of the rolls upon the work, cause, by their co-operation, the rolls to come to rest in predetermined relative angular positions.

4. An appliance for rolling a screw thread upon a revolving work-piece comprising a roll carrier movable laterally towards the work, a pair of rotating spindles mounted upon the carrier, screw-threaded rolls rigid with the spindles,'and spring-loaded members engaging ends of the spindles, one of the engaging parts between each spring loaded member and spindle consisting of a transverse projection and the other having a vsectioned recess engaged by the projection, and the sloping sides of the recess acting as cam surfaces co-operating with the transverse projection to bring the rolls to rest in predetermined relative angular positions.

5. An appliance for ,rolling a screw thread upon a revolving work-piece comprising a roll carrier movable laterally towards the work, a pair of rotating spindles mounted upon the carrier, screw-threaded rolls rigid with the spindles, and spring-loaded members provided with V-shaped projections engaging ends of thespindles, the

engaging end of each spindle being formed with g a V-shaped transverse projection engaging in a V-sectioned groove in the V-shaped projection of each spring-loaded member.

6. An appliance for rolling a screw thread upon a revolving work-piece comprising a roll carrier movable laterally towards the work, a pair of rotating spindles mounted upon the carrier, screw-threaded rolls rigid with the spindles, spring-loaded members pressing axially on ends of the spindles, roll-positioning means between said members and said spindles consisting of a V-sectioned rib on one part engaging a V-sectioned groove in the other part, and springs acting upon the ends of the spindles opposite to those ends engaged by the spring-loaded members, said springs exerting an axial pressure tending to counteract the end thrust upon the rolls caused by the said spring-actuated members.

GEORGE GOULD. 

